That’s a common question of late. Leeches can be a pest, sucking blood and creating sores by which other diseases can get in and cause severe disease and death in fish.
What are some chemicals that would work, to kill the parasites that are still safe for the fish? Organophosphates like trichlorfon and fenthion would work. Copper sulphate works against all invertebrates. Flubendazole would work, but it’s not available in Australia.
Dr Ypelaan added a non-chemical way.
Set a trap using a container with raw meat, and nail holes to allow leeches in but not out.
Have I left anything out?
